Question

a circuit contains two light bulbs connected in parallel. what would happen to the brightness of each light bulb if two more light bulbs were added in parallel to the first ones? the brightness of each bulb would decrease because the total resistance of the circuit would decrease. the brightness of each bulb would increase because the total resistance of the circuit would increase. the brightness of each bulb would remain the same even though the total resistance of the circuit would decrease. the brightness of each bulb would remain the same even though the total resistance of the circuit would increase.

Explanation:

In a parallel - connected circuit, the voltage across each component is the same. Adding more bulbs in parallel decreases the total resistance of the circuit according to the formula for parallel resistors $\frac{1}{R_{total}}=\sum_{i = 1}^{n}\frac{1}{R_i}$. But since the voltage across each individual bulb remains unchanged (as it is connected across the same voltage source in parallel), and the power of a bulb $P=\frac{V^{2}}{R}$ (where $V$ is the voltage across the bulb and $R$ is its resistance). As $V$ is constant for each bulb in parallel regardless of the number of bulbs added in parallel, the brightness (which is related to power) of each bulb remains the same.

Answer:

The brightness of each bulb would remain the same even though the total resistance of the circuit would decrease.